At present the principal tumor treatment methods include surgical, chemotherapeutic, and radiation approaches. Surgical approach is efficient in cases of early diagnosis and smaller tumors without remote metastases. Large, advanced tumors may be removed only in rare cases, and this approach is often impossible.
The preferred method of conservative treatment of malignant tumors includes selective chemotherapy performed by injection of antitumor preparations into the blood vessels that supply the tumor, or directly into the tumor tissue or peritumoral region.
Known in the art is the method of treatment of malignant kidney tumors including chemoembolization of arterial network of the diseased kidney using an oil solution containing 100 mg of the anticancer substance Dioxadet, followed by occlusion of the main branch of the renal artery by a metal coil. Such chemoembolization leads to a reliable increase in the corrected indices of 3- and 5-year cumulative survival in patients with inoperable cancer of kidney parenchyma to 33.0.+-.6.9% and 24.5.+-.6.75 respectively, in comparison with the convenient embolization methods without a chemo-therapeutic component, where these indices are 10.6.+-.4.2% and 0% (Anisimov V. A., et al. In: Modern Techniques in Roentgenosurgery, Abstr. IX Nat. Symp., Moscow, 1989, P. 118-119). However, gradually increasing intoxication caused by tumor decomposition sharply aggravates the patient's condition. Besides this, along with the tumor degradation products, tumor cellular elements are liberated into the venal bloodstream and lymphatic system, and may cause metastases.
Known in the art is a method of treatment of malignant liver tumors which includes embolization of the hepatic artery by a metal coil after the injection of Dioxadet (30-50 mg) dissolved in 6-9 ml of Myodil into its arterial branches (Granov A. M., Borisov A. E. In: "Endovascular Surgery of the Liver", Moscow, Meditsina, 1986, p. 137-138). Intraarterial infusion of chemo-therapeutic agents provides better results as compared to intraportal infusion, since malignant tumors of the liver are supplied mainly by the arterial blood system. Therefore the intraarterial injection received wider application.
According to the inventors' data, remissions last up to 6-8 months, and one-year survival in patients with unresectable malignant tumors was 56.2%. The duration of remissions reported in the world medical literature for selective chemotherapy is 4-12 months. Anticancer substances are known to be toxic, especially when used systemically. The use of oil solutions somewhat reduces the general intoxication of the body due to retarded supply of a chemotherapeutic agent from an oil into tissues around the tumor. However, in spite of this fact, the decomposition of tumor tissue induced by chemotherapeutics, especially in bulky tumors, leads to sufficiently high intoxication and therefore worsens the general condition of a patient. Localization of an oil solution of chemotherapeutic agent in the tumor tissue for a period of 20-25 days often proves insufficient for the complete death of tumor cells. This disadvantage is further increased by the fact that oil solution eventually dissipates from the tumor. It brings about the need of repetitive intraorganous injections of a preparation and, as a consequence, yet more increase of intoxication.
Known in the art is also a method of treatment of hepatomas by chemoembolization using ferromagnetic particles followed by hyperthermia (Sako M., Hirota S. Gan To Kogaku Ryoho, 1986, vol. 13, No. 4, pt. 2, p. 1618-1624). Chemotherapeutic agent is administered into hepatic artery within the mixture containing a solution of carboxymethylcellulose or dextrane in a saline aqueous medium, and magnetically soft substance, metal iron, in the form of particles 30-50 mcm in size. The composition is confined within the tumor area by a local magnetic field. Hyperthermia is performed by induction heating of the magnetic particles. However, the large size of particles necessary for efficient induction heating (30-50 mcm) causes occlusion of the precapillary zone of the tumor. Therefore the prerequisites are created for preservation of viable parts of the tumor. Magnetically soft material may migrate out of the tumor area and dissipate in the course of tumor degradation. This phenomenon may lead to undesirable microembolizations. The use of water-based solutions of chemotherapeutic agents is known to provide a less pronounced prolongation effect because of the faster diffusion into tissues with consequent washing out of the organ. This process is increased by preserved organ blood flow. Beside this, the dissipation of ferromagnetic from the tumor area is inconvenient for monitoring of the tumor in remote periods and excludes the possibility of repeated hyperthermia procedures that may prove necessary. All said reasons increase probability of the tumor recurrence.
Known in the art is also the experimentally tested method of reduction of the tumor mass, based on the delivery into a tumor of magnetically hard ferromagnetic material using magnetic field, with consequent heating of the tumor at the expense of heat emitted by this ferromagnetic when placed into low-frequency oscillating electromagnetic field (U.S. Pat. No. 4,323,056). However, the said method employs heat treatment of a tumor alone, which, as evidenced by many reported data, is insufficient for complete necrosis and death of tumor cells.
Therefore, none of the known methods can provide complete necrosis of the tumor lesion without considerable intoxication and the risk of metastatic offspread.